| In order to improve load-bearing capacity of internal combustion engine's piston pin seat,piston pin hole is designed as bell mouth and ellipse,which satisfies the high load demand of the engine.With the increase of engine emissions and power requirements,the load-bearing capacity of the piston pin seat puts forward higher request,structural type of piston pin also becomes more complex,the main features is:pin hole section changes into variable ellipse or curve combined profile from standard ellipse.For standard elliptical hole machining,it is necessary to ensure that the spindle axis of the boring spindle is in a certain angle.However,when variable elliptic pin hole is processed,it needs to be changed with the tilt Angle,which will change other size of pin hole,and it cannot realize processing of the curve combined profile.In order to achieve this,radial feed system has the following requirements:(1)the largest radial displacement should be greater than 100?m;(2)natural frequency of system should be not less than 100Hz.In this paper a radial micro-displacement feed system with asymmetric structure deformable body is designed and analyzed.Firstly,SolidWorks is used to establish model of deformable body.Finite element analysis is done based on Workbench,and multi-objective optimization method is adopted to optimize the design and static balance and dynamic balance are achieved.The maximum radial displacement increased to 127?m to meet requirement.Secondly,the characteristics of hydraulic pipeline and servo valve are analyzed separately,and the characteristics of the hydraulic pipeline are verified to meet the requirements,and the natural frequency of the hydraulic pipeline is only related to the length of pipeline.Then coupling analysis of the system,pipeline characteristics are considered,and pipeline characteristics are modified by dynamic friction and static friction.Bond graph model of pressure servo system is established based on bond graph method,mathematical model of pressure servo system is deduced and system characteristics are analyzed.Natural frequency of system is 186Hz,which is greater than 100Hz.Then,reason of chatter is analyzed,and stability of boring processing system is analyzed based on Lobe diagram.Based on impact damping principle,impact damper is designed to improve the stability of system.Finally,characteristics of non-circular pin hole and interpolation methods are analyzed,boring machine based on TwinCAT is introduced,including the design of pressure servo system and selection of main components,as well as the design of NC system's hardware architecture and surface processing software scheme,and then the verification experiment is done,and experimental result is analyzed. |
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